A Geek In Paradise

A trip to see the particle accelerator at Fermilabs by a self-professed geek.

I had been to Fermilab only the year
before, but when the invitation came from Dan Yocum to meet at
Fermilab's facility outside Chicago, how could I refuse? I am a
geek at heart.

Figure 1. Fermi Campus

Fermilab is short for “Fermi National Accelerator
Laboratory”, located in Batavia, Illinois. It occupies a parcel of
land about three miles on each side (see Figure 1), and houses
several accelerator rings which generate (in a
very concentrated space) amounts of power
greater than those found in the sun or any other place in the
galaxy, much less on the face of the earth. They use these
fantastic amounts of power to collide various particles at
extremely high speed in the search for the basic building blocks of
the universe.

In ancient days, various philosophers stated that we would
eventually find the “smallest particle”, and for a while this was
considered to be the atom. In the relatively recent days of
discovering nuclear energy, it was recognized that the smallest
particle was not the atom, but made up of
various other parts such as protons, neutrons and electrons.
(Students of physics, please have mercy on me as I try to explain
this in words that most readers will understand.) During the last
quarter of a century, more and more physicists began to believe
there were even smaller particles making up the protons, called
quarks and gluons. Quarks (having nothing to do with a resident of
Deep Space Nine) are thought to have six
different types, and in 1994 the last of these Quarks, the “top
quark”, was discovered at Fermilab. Unfortunately, the top quark
exists for only a very short (10 -24 seconds) period of time, so it
is very hard to collect data on it, particularly when it is seen
only six times in a given year of running the accelerator.
Therefore, Fermilab decided to increase the size and power of its
accelerator, so it could see anywhere from 20 to 300 times the
number of quarks. Unfortunately, this would take anywhere from 20
to 300 times the amount of power and generate 20 to 300 times the
amount of raw data to be seen by the collectors, meaning
1,000,000MB of data would be generated every second. Yes, that is
one million megabytes of data per second.

Of course, storing that much data would be very difficult,
but fortunately Fermilab had determined they would be able to
filter the information and store a smaller subset of it (only 18 to
100MB of data per second) for later analysis. To do this, they
would have to increase the power of their computing systems
significantly, and their former model of using expensive
workstations in a workstation farm would not have been affordable.
Enter Linux.

Figure 3. Fermi main building.

Last year, when people from Red Hat Software and I visited
Fermilab while attending Spring Comdex, I was lucky enough to meet
G. P. Yeh, a big fan of Linux and one of the physicists who
discovered the top quark. He was kind enough to take us on a short
tour of the Fermilab facilities and explain the role of Linux
within Fermilab. He explained they investigated Linux and proved
that inexpensive PCs running Linux could do the job more than
adequately for a price they could afford. They estimated they would
need about 2,000 CPUs working together.

Figure 4. Collider Rings

This year, when Dan Yocum heard that Linus Torvalds was
speaking at Spring Comdex, he enlisted my help in convincing Linus
to make a separate trip to Fermilab to speak to the physicists and
their families. This did not take much convincing, since Linus has
an interest in math, physics and science.

Figure 5. Computer Room-stacks of Linux boxes

We met at the hotel where Linus was staying, and with a small
group of Linux supporters (see Figure 2), drove to Fermilab. It is
quite interesting to approach Fermilab, since the land around the
accelerator is flat, with only the main building (see Figure 3)
rising up from the ground to any height. It would definitely be a
great scene for a science fiction movie. We parked the car, went
inside and met Dr. G. P. Yeh (who everyone calls “G.P.”).

G.P. took us on an extended tour, beginning with the top
floor of the main building, looking out over the collider rings.
“As far as you can see in every direction is Fermilab”, G.P.
said. It was an impressive sight. He then took us to see the
collider detectors (see Figure 4)—“It weighs only 100 tons and
cost about 100 million dollars.” Finally, we visited the computer
room, where the Linux Farms were going to be placed (see Figures 5
and 6). Fermilab calls their systems “Farms” rather than Beowulf
systems. They have master machines that delegate the work to many
slave processors, connected by high-speed networking and switches.
They are not planning on buying the 2000 CPUs until very close to
the time they need them. After all, prices keep dropping and
capabilities keep increasing, so why not wait until the last moment
to get the best “bang for the buck”?

After the tour was over, we went to the main auditorium where
Linus gave his talk. For those of you who have heard Linus give a
speech, you know he does not like to talk with prepared slides, but
instead gives a short prepared talk, then answers questions. This
night was no different, other than the topic and complexity of the
questions. It was obvious from the questions asked that the
audience had more of a computer science bent than other, more
general audiences. Questions regarding symmetric multi-processing
and the reality of distributing interrupts over multiple CPUs
entered the air.

After a significant amount of time answering questions and
signing autographs, our little troupe went to the home of Jeff
Gerhardt to enjoy pizza and “refreshments”. We were greeted by
smoke rolling out of the front door, reminding everyone it is best
to take the pizza out of the box before warming it in the oven.
When the smoke died down, some interesting home brew made its way
to the front, and everyone enjoyed the pizza and brew (see Figures
7 and 8).

Figure 7. Party Time: Linus on left by lamp, G.P. Yeh in far chair,
Stefan Traby in far right